Non-contact seal assembly with multiple spaced spring elements

ABSTRACT

An assembly is provided for rotational equipment. This assembly includes a plurality of seal shoes, a seal base and a spring system. The seal shoes are arranged about a centerline in an annular array. The seal shoes include a first seal shoe. The seal base circumscribes the seal shoes. The spring system connects the seal shoes to the seal base. The spring system includes a first spring element and a second spring element. The first spring element extends axially along the centerline in a first axial direction from the seal base to the first seal shoe. The second spring element extends axially along the centerline in a second axial direction from the seal base to the first seal shoe. The second axial direction is opposite the first axial direction.

This application claims priority to U.S. patent application Ser. No.16/919,444 dated Jul. 2, 2020 which is hereby incorporated herein byreference in its entirety.

BACKGROUND OF THE DISCLOSURE 1. Technical Field

This disclosure relates generally to rotational equipment and, moreparticularly, to a non-contact seal for the rotational equipment.

2. Background Information

Rotational equipment typically includes one or more seal assemblies forsealing gaps between rotors and stators. A typical seal assemblyincludes a contact seal with a seal element such as a knife edge sealthat engages a seal land. Such a contact seal can generate a significantquantity of heat that can reduce efficiency of the rotational equipmentas well as subject other components of the rotational equipment to hightemperatures and internal stresses. To accommodate these hightemperatures and stresses, certain components of the rotationalequipment may be constructed from specialty high temperature materials.However, these materials can significantly increase manufacturing andservicing costs as well as mass of the rotational equipment. Whilenon-contact seals have been developed in an effort to reduce heat withinrotational equipment, there is still room for improvement to provide animproved non-contact seal. In particular, there is room in the art for anon-contact seal with reduced or no frictional rubbing.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, an assembly isprovided for rotational equipment. This assembly includes a plurality ofseal shoes, a seal base and a spring system. The seal shoes are arrangedabout a centerline in an annular array. The seal shoes include a firstseal shoe. The seal base circumscribes the seal shoes. The spring systemconnects the seal shoes to the seal base. The spring system includes afirst spring element and a second spring element. The first springelement extends axially along the centerline in a first axial directionfrom the seal base to the first seal shoe. The second spring elementextends axially along the centerline in a second axial direction fromthe seal base to the first seal shoe. The second axial direction isopposite the first axial direction.

According to another aspect of the present disclosure, another assemblyis provided for rotational equipment. This assembly includes a pluralityof seal shoes, a seal base and a spring system. The seal shoes arearranged about a centerline in an annular array. The seal shoes includea first seal shoe. The seal base extends circumferentially around theseal shoes and the centerline. The spring system connects the seal shoesto the seal base. The spring system includes a first spring element anda second spring element. The first spring element is axially between andconnected to the seal base and the first seal shoe. The second springelement is axially between and connected to the seal base and the firstseal shoe. The first seal shoe is axially between the first springelement and the second spring element.

According to still another aspect of the present disclosure, anotherassembly is provided for rotational equipment. This assembly includes aplurality of seal shoes, a seal base and a spring system. The seal shoesare arranged about a centerline in an annular array. The seal shoesinclude a first seal shoe and a second seal shoe. The seal base extendscircumferentially around the plurality of seal shoes and the centerline.The spring system connects the seal shoes to the seal base. The springsystem includes a first spring element, a second spring element, a thirdspring element and a fourth spring element. The first spring element isarranged towards a first axial side of the first seal shoe. The firstspring element is connected to and is between the first seal shoe andthe seal base. The second spring element is arranged towards a secondaxial side of the first seal shoe. The second spring element isconnected to and is between the first seal shoe and the seal base. Thethird spring element is arranged towards a first axial side of thesecond seal shoe. The third spring element is connected to and isbetween the second seal shoe and the seal base. The fourth springelement is arranged towards a second axial side of the second seal shoe.The fourth spring element is connected to and is between the second sealshoe and the seal base. The first seal shoe and the second seal shoe arelaterally separated by a first lateral distance. The first springelement and the third spring element are laterally separated by a secondlateral distance that is equal to the first lateral distance.

The seal base may include a first flange that radially overlaps thefirst seal shoe. The first spring element may extend axially from thefirst flange to the first seal shoe.

The seal base may also include a second flange that radially overlapsthe first seal shoe. The second spring element may extend axially fromthe second flange to the first seal shoe.

A first radius may extend from the centerline to the first springelement. A second radius may extend from the centerline to the secondspring element. The first radius may be equal to (or different than) thesecond radius.

The assembly may also include a compression spring between and engagedwith the seal base and the first spring element.

The assembly may also include a compression spring between and engagedwith the seal base and the first seal shoe.

The assembly may also include a damper between and connected to the sealbase and the first seal shoe.

The seal base may include a seal shoe stop configured to limit radialoutward movement of the first seal shoe.

A vent aperture may extend through the seal shoe stop.

A vent aperture may extend through the first spring element.

A vent aperture may extend through the first seal shoe.

The first seal shoe may project axially beyond the seal base.

The first spring element may extend axially along the centerline in thefirst axial direction from the seal base to the first seal shoe for afirst axial distance. The second spring element may extend axially alongthe centerline in the second axial direction from the seal base to thefirst seal shoe for a second axial distance. The second axial distancemay be different than (or equal to) the first axial distance.

The first spring element may have a straight, linear sectional geometryas the first spring element extends from the seal base to the first sealshoe. In addition or alternatively, the second spring element may have astraight, linear sectional geometry as the second spring element extendsfrom the seal base to the first seal shoe.

At least a portion of the first spring element may have a tortuoussectional geometry as the first spring element extends away from theseal base towards the first seal shoe. In addition or alternatively, atleast a portion of the second spring element may have a tortuoussectional geometry as the second spring element extends away from theseal base towards the first seal shoe.

The spring system may also include one or more additional springelements connected to and extending between the seal base and the firstseal shoe.

The first seal shoe may have a first seal shoe lateral width. The firstspring element may have a first spring element lateral width that isequal to the first seal shoe lateral width. In addition oralternatively, the second spring element may have a second springelement lateral width that is equal to the first seal shoe lateralwidth.

The assembly may also include a stationary structure, a rotatingstructure and a seal assembly. The rotating structure may be configuredto rotate about the centerline. The seal assembly may include the sealshoes, the seal base and the spring system. The seal assembly may beconfigured to seal a gap between the stationary structure and therotating structure. The seal shoes may be arranged circumferentiallyabout and sealingly engage the rotating structure. The seal base may bemounted to the stationary structure.

The present disclosure may include any one or more of the individualfeatures disclosed above and/or below alone or in any combinationthereof

The foregoing features and the operation of the invention will becomemore apparent in light of the following description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial side sectional illustration of an assembly forrotational equipment.

FIG. 2 is a high pressure side (HPS) end view illustration of a sealassembly of the rotational equipment assembly.

FIG. 3 is a partial side sectional illustration of the seal assembly.

FIG. 4 is an HPS end view illustration of a portion of the seal assemblyincluding a seal shoe and a portion of an HPS spring element.

FIG. 5 is a low pressure side (LPS) end view illustration of a portionof the seal assembly including the seal shoe and a portion of an LPSspring element.

FIG. 6 is an HPS end view illustration of a portion of the seal assemblyincluding two neighboring seal shoes and two neighboring HPS springelements.

FIG. 7 is an LPS end view illustration of a portion of the seal assemblyincluding the two neighboring seal shoes and two neighboring LPS springelements.

FIG. 8 is a partial side sectional illustration of a prior art sealassembly.

FIG. 9 is a side sectional illustration of a spring element betweenopposing portions of the seal assembly of the present disclosure.

FIG. 10 is a side sectional illustration of another spring elementbetween opposing portions of the seal assembly.

FIG. 11 is a side sectional illustration depicting an interface betweenHPS and LPS spring elements and a seal shoe.

FIG. 12 is a side sectional illustration depicting another interfacebetween the HPS and the LPS spring elements and the seal shoe.

FIG. 13 is a side sectional illustration of another spring elementbetween opposing portions of the seal assembly.

FIG. 14 is a side sectional illustration depicting HPS and LPS springelements connecting a seal shoe with a seal base.

FIG. 15 is a side sectional illustration depicting another interfacebetween the HPS and the LPS spring elements and the seal shoe.

FIG. 16 is a side sectional illustration depicting still anotherinterface between the HPS and the LPS spring elements and the seal shoe.

FIG. 17 is a partial side sectional illustration of the seal assemblyconfigured with a seal shoe stop and a plurality of compression springs.

FIG. 18 is a partial side sectional illustration of the seal assemblyconfigured with a seal shoe stop, a compression spring and a pluralityof vent apertures.

FIG. 19 is a partial side sectional illustration of the seal assemblyconfigured with a compression spring and a damper.

FIG. 20 is a partial side sectional illustration of the seal assemblyconfigured with an extended seal shoe.

FIG. 21 is a partial side sectional illustration of the seal assemblyconfigured with one or more additional spring elements.

FIG. 22 is a side cutaway illustration of a gas turbine engine which maybe configured with the rotational equipment assembly.

DETAILED DESCRIPTION

FIG. 1 illustrates an assembly 30 for rotational equipment with an axialcenterline 32, which centerline 32 may also be an axis of rotation(e.g., a rotational axis) for one or more components of the rotationalequipment assembly 30. An example of such rotational equipment is a gasturbine engine for an aircraft propulsion system, an exemplaryembodiment of which is described below in further detail (e.g., see FIG.22). However, the rotational equipment assembly 30 of the presentdisclosure is not limited to such an aircraft or gas turbine engineapplication. The rotational equipment assembly 30, for example, mayalternatively be configured with rotational equipment such as anindustrial gas turbine engine, a wind turbine, a water turbine or anyother apparatus in which a seal is provided between a stationarystructure and a rotating structure; e.g., a rotor.

The rotational equipment assembly 30 of FIG. 1 includes a stationarystructure 34, a rotating structure 36 and a seal assembly 38 such as,for example, an adaptable non-contact seal assembly. The seal assembly38 is mounted with the stationary structure 34 and configured tosubstantially seal an annular gap between the stationary structure 34and the rotating structure 36 as described below in further detail.

The stationary structure 34 includes a seal carrier 40. This sealcarrier 40 may be a discrete, unitary annular body. Alternatively, theseal carrier 40 may be configured with another component/portion of thestationary structure 34. The seal carrier 40 has a seal carrier innersurface 42. This seal carrier inner surface 42 may be substantiallycylindrical. The seal carrier inner surface 42 extends circumferentiallyabout (e.g., completely around) and faces towards the axial centerline32. The seal carrier inner surface 42 at least partially forms a bore inthe stationary structure 34. This bore is sized to receive the sealassembly 38, which may be fixedly attached to the seal carrier 40 by,for example, a press fit connection between the seal assembly 38 and theseal carrier inner surface 42. The seal assembly 38, of course, may alsoor alternatively be fixedly attached to the seal carrier 40 using one ormore other techniques/devices.

The rotating structure 36 includes a seal land 44. This seal land 44 maybe a discrete, unitary annular body. For example, the seal land 44 maybe mounted to a shaft of the rotating structure 36. Alternatively, theseal land 44 may be configured with another component/portion of therotating structure 36. For example, the seal land 44 may be an integralpart of a shaft of the rotating structure 36, or another componentmounted to the shaft.

The seal land 44 of FIG. 1 has a seal land outer surface 46. This sealland outer surface 46 may be substantially cylindrical. The seal landouter surface 46 extends circumferentially about (e.g., completelyaround) and faces away from the axial centerline 32. The seal land outersurface 46 is configured to face towards and is axially aligned with theseal carrier inner surface 42. While FIG. 1 illustrates the seal landouter surface 46 and the seal carrier inner surface 42 withapproximately equal axial lengths along the axial centerline 32, theseal land outer surface 46 may alternatively be longer or shorter thanthe seal carrier inner surface 42 in other embodiments.

The seal assembly 38 is configured as an annular seal assembly such as,but not limited to, a non-contact hydrostatic seal device. The sealassembly 38 of FIG. 1 includes a seal base 48, a plurality of seal shoes50 and a spring system 52.

The seal base 48 may be configured as an annular full hoop body. Theseal base 48 of FIG. 2 extends circumferentially about (e.g., completelyaround) the axial centerline 32. The seal base 48 is configured toextend circumferentially around and thereby circumscribe and support theseal shoes 50 as well as the spring system 52 and its components (e.g.,spring elements); see FIG. 3. Referring to FIG. 3, the seal base 48extends axially along the axial centerline 32 between and forms a sealbase high pressure side (HPS) end 54 and a seal base low pressure side(LPS) end 56. The seal base 48 extends radially between and forms a sealbase inner side 58 and a seal base outer side 60, where a surface 62 ofthe seal base 48 at the seal base outer side 60 radially engages (e.g.,is press fit against or otherwise contacts) the stationary structure 34and its inner surface 42.

The seal base 48 may have a generally U-shaped sectional geometry. Theseal base 48 of FIG. 3, for example, includes an outer tubular base 64,a high pressure side (HPS) flange 66 (e.g., an annular rim) and a lowpressure side (LPS) flange 68 (e.g., an annular rim). The outer tubularbase 64 is arranged at (e.g., on, adjacent or proximate) the seal baseouter side 60. The outer tubular base 64 extends axially along the axialcenterline 32 between and to the seal base HPS end 54 and the seal baseLPS end 56. The HPS flange 66 is arranged at the seal base HPS end 54.The HPS flange 66 projects radially inwards, towards the axialcenterline 32, from the outer tubular base 64 to a distal end at theseal base inner side 58. The LPS flange 68 is arranged at the seal baseLPS end 56. The LPS flange 68 projects radially inwards, towards theaxial centerline 32, from the outer tubular base 64 to a distal end atthe seal base inner side 58. Each of the flanges 66 and 68 may extendcircumferentially about (e.g., completely around) the axial centerline32.

With the foregoing configuration, a (e.g., annular) channel 70 is formedin the seal base 48. This channel 70 extends partially radially, in anoutward direction away from the axial centerline 32, into the seal base48 from the seal base inner side 58 to an inner surface 72 of the outertubular base 64. The channel 70 extends within the seal base 48 axiallyalong the axial centerline 32 between opposing surfaces 74 and 76 of theHPS and the LPS flanges 66 and 68. The channel 70 extends within theseal base 48 circumferentially about (e.g., completely around) the axialcenterline 32.

In some embodiments, one or more of the flanges 66, 68 may include oneor more vent apertures; e.g., through-holes. The LPS flange 68 of FIG.3, for example, includes one or more vent apertures 78 (one visible inFIG. 3), which vent apertures 78 are arranged circumferentially aboutthe axial centerline 32. Each of the vent apertures 78 extends axiallythrough the LPS flange 68 so as to fluidly couple a plenum 80 within theseal base 48 (e.g., within the channel 70) with a plenum 82 outside ofthe seal assembly 38 and next to the seal base LPS end 56.

Referring to FIG. 2, the seal shoes 50 may be configured as arcuatebodies and are arranged circumferentially around the axial centerline 32in an annular array. Each of the seal shoes 50, for example, is arrangedcircumferentially between and next to a pair of adjacentcircumferentially neighboring seal shoes 50. The annular array of theseal shoes 50 extends circumferentially about (e.g., completely around)the axial centerline 32, thereby forming an inner bore at an inner side84 of the seal assembly 38. As best seen in FIG. 1, the inner bore issized to receive the seal land 44, where the rotating structure 36projects axially through (or into) the inner bore formed by the sealshoes 50.

Referring to FIGS. 4 and 5, each of the seal shoes 50 extends radiallyfrom the inner side 84 of the seal assembly 38 to an outer side 86 ofthat seal shoe 50. Each of the seal shoes 50 extends circumferentiallyabout the axial centerline 32 between and to opposing ends 88A and 88B(generally referred to as “88”) of that seal shoe 50. Referring to FIG.3, each of the seal shoes 50 extends axially along the axial centerline32 between a high pressure side (HPS) side 90 and a low pressure side(LPS) side 92 of the seal shoe 50. The seal shoe HPS side 90 is anupstream side relative to, for example, flow of leakage fluid across theseal assembly 38. The seal shoe LPS side 92 is a downstream siderelative to, for example, the flow of leakage fluid across the sealassembly 38.

Each of the seal shoes 50 includes a seal shoe base 94 and one or moreseal shoe projections 96A-C (generally referred to as “96”) (e.g.,rails/teeth). Each seal shoe 50 of FIG. 3 also includes a seal shoemount 98. The seal mount 98, however, may be omitted where, for example,the spring system 52 is connected directly to the seal shoe base 94.

The seal shoe base 94 extends axially along the axial centerline 32between the seal shoe HPS side 90 and the seal shoe LPS side 92. Theseal shoe base 94 extends radially between and to one or more (e.g.,arcuate) base outer surfaces 100A and 100B (generally referred to as“100”) and one or more base inner surfaces 102A-C (generally referred toas “102”). Each of these base inner surfaces 102 may be an arcuatesurface. Referring to FIGS. 4 and 5, the seal shoe base 94 extendscircumferentially about the axial centerline 32 between and to the sealshoe ends 88A and 88B. The seal shoe base 94 includes a first endsurface at the seal shoe end 88A and a second end surface at the sealshoe end 88B. Each of the end surfaces may be a flat planar surface.Each of the end surfaces, for example, may have a straight sectionalgeometry when viewed, for example, in a plane perpendicular to the axialcenterline 32; e.g., the plane of FIG. 4 or 5.

Referring to FIG. 3, the seal shoe projections 96 are arranged atdiscrete axial locations along the axial centerline 32 and the seal shoebase 94. Each pair of axially adjacent/neighboring projections 96 maythereby be axially separated by an (e.g., arcuate) inter-projection gap.The seal shoe projections 96 of FIG. 3 are configured parallel to oneanother.

The seal shoe projections 96 are connected to (e.g., formed integralwith or otherwise attached to) the seal shoe base 94. Each of the sealshoe projections 96 projects radially inwards, towards the axialcenterline 32, from the seal shoe base 94 and its base inner surfaces102 to a distal projection end.

Each of the seal shoe projections 96 has a projection inner surface104A-C (generally referred to as “104”) at the distal projection end.One or more or each of the projection inner surfaces 104 may be at theinner side 84 of the seal assembly 38. Each projection inner surface 104may be an arcuate surface. Each projection inner surface 104, forexample, may have an arcuate sectional geometry when viewed, forexample, in a plane perpendicular to the axial centerline 32; e.g., theplane of FIG. 4 or 5. One or more or each of the projection innersurfaces 104 is configured to be arranged in close proximity with (butnot touch) and thereby sealingly mate with the seal land outer surface46 in a non-contact manner (see FIG. 1), where the rotating structure 36projects axially through (or into) the inner bore formed by the sealshoes 50.

Each of the seal shoe projections 96 of FIG. 3 extends axially betweenopposing projection end surfaces. Each of these end surfaces extendsradially between and may be contiguous with a respective one of theprojection inner surfaces 104 and a respective one of the base innersurfaces 102.

One or more of the seal shoe projections 96 may have a different radialheight than at least another one of the seal shoe projections 96. Forexample, the radial height of the intermediate projection 96B may begreater than the radial heights of the end projections 96A and 96C. Theradial heights of the end projections 96A and 96C may be equal ordifferent from one another. Of course, in other embodiments, each of theseal shoe projections 96 may have the same radial height.

The seal shoe mount 98 of FIG. 3 projects radially outward, away fromthe axial centerline 32, from the seal shoe base 94 and its base outersurface 100 to a distal end at the seal shoe outer side 86. The sealshoe mount 98 extends axially along the axial centerline 32 betweenopposing mount sides 106 and 108. Referring to FIGS. 4 and 5, the sealshoe mount 98 extends circumferentially about the axial centerline 32between the opposing seal shoe ends 88. Referring again to FIG. 3, theseal shoe mount 98 is disposed a (e.g., non-zero) first axial distance110 from the seal shoe HPS side 90 and a (e.g., non-zero) second axialdistance 112 from the seal shoe LPS side 92. In the embodiment of FIG.3, the first axial distance 110 is different (e.g., less, oralternatively greater) than the second first axial distance 112. Thepresent disclosure, however, is not limited to such an exemplaryembodiment. For example, in other embodiments, the first axial distance110 may be equal to the second first axial distance 112.

The spring system 52 includes a plurality of spring element groupings,where each of the groupings is (e.g., uniquely) associated with arespective one of the seal shoes 50. For example, each of the springelement groupings is configured to respectively moveably and resilientlyconnect a respective one of the seal shoes 50 to the seal base 48. Eachof the spring element groupings may include a plurality of springelement 114 and 116; e.g., spring beams such as, but not limited to,leaf springs, cantilevered springs, etc.

The high pressure side (HPS) spring element 114 is arranged towardsand/or on the seal shoe HPS side 90. The HPS spring element 114 of FIG.3, for example, is arranged (e.g., axially) between and connected to theseal base 48 and a respective seal shoe 50. More particularly, the HPSspring element 114 is connected to (e.g., formed integral with orotherwise attached to) the HPS flange 66 and the seal shoe mount 98. TheHPS spring element 114 of FIG. 3 extends axially along the axialcenterline 32 in a first axial direction 118 (e.g., left-to-right inFIG. 3) from the HPS flange 66 to the seal shoe mount 98.

Referring to FIG. 4, the HPS spring element 114 extends radially betweenopposing inner and outer sides 120 and 122 of that HPS spring element114. The HPS spring element 114 extends circumferentially betweenopposing sides 124A and 124B (generally referred to as “124”) of the HPSspring element 114. Each of the HPS spring element sides 124A, 124B maybe circumferentially aligned with a respective one of the seal shoesides 88A, 88B. With such a configuration, a lateral width 126 of theseal shoe 50 connected to the HPS spring element 114 may be exactlyequal to or substantially equal to (e.g., +/−1% or 2%) a lateral width128 of the HPS spring element 114 at, for example, a common and/orproximate radial location. Referring to FIG. 6, this enables a lateralwidth 130 of a gap (i.e., a lateral distance) between laterallyneighboring HPS spring elements 114 to be exactly equal to orsubstantially equal to (e.g., +/−1% or 2%) a lateral width 132 of a gap(i.e., a lateral distance) between laterally neighboring seal shoes 50.Thus, the HPS spring elements 114 may substantially seal a gap betweenthe seal base 48 and the seal shoes 50.

Referring to FIG. 3, the low pressure side (LPS) spring element 116 isarranged towards and/or on the seal shoe LPS side 92. The LPS springelement 116 of FIG. 3, for example, is arranged (e.g., axially) betweenand connected to the seal base 48 and a respective seal shoe 50. Moreparticularly, the LPS spring element 116 is connected to (e.g., formedintegral with or otherwise attached to) the LPS flange 68 and the sealshoe base 94. The LPS spring element 116 of FIG. 3 extends axially alongthe axial centerline 32 in a second axial direction 134 (e.g.,right-to-left in FIG. 3) from the LPS flange 68 to the seal shoe base94, where the second axial direction 134 is opposite the first axialdirection 118. With this configuration, the seal shoe 50 is arrangedaxially between the LPS spring element 116 and the HPS spring element114.

Referring to FIG. 5, the LPS spring element 116 extends radially betweenopposing inner and outer sides 136 and 138 of that LPS spring element116. The LPS spring element 116 extends circumferentially betweenopposing sides 140A and 140B (generally referred to as “140”) of the LPSspring element 116. Each of the LPS spring element sides 140A, 140B maybe circumferentially aligned with a respective one of the seal shoesides 88A, 88B. With such a configuration, a lateral width 142 of theseal shoe 50 connected to the LPS spring element 116 may be exactlyequal to or substantially equal to (e.g., +/−1% or 2%) a lateral width144 of the LPS spring element 116. Referring to FIG. 7, this enables alateral width 146 of a gap (i.e., a lateral distance) between laterallyneighboring LPS spring elements 116 to be exactly equal to orsubstantially equal to (e.g., +/−1% or 2%) a lateral width 148 of a gap(i.e., a lateral distance) between laterally neighboring seal shoes 50.Thus, the LPS spring elements 116 may substantially seal a gap betweenthe seal base 48 and the seal shoes 50.

During operation of the seal assembly 38 of FIG. 1, rotation of therotating structure 36 may develop aerodynamic forces and apply a fluidpressure to the seal shoes 50 causing each seal shoe 50 to respectivelymove radially relative to the seal land outer surface 46. The fluidvelocity may increase as a gap between a respective seal shoe 50 and theseal land outer surface 46 increases, thus reducing pressure in the gapand drawing the seal shoe 50 radially inwardly toward the seal landouter surface 46. As the gap closes, the velocity may decrease and thepressure may increase within the gap, thus, forcing the seal shoe 50radially outwardly from the seal land outer surface 46. The respectivespring elements 114 and 116 may deflect and move with the seal shoe 50to enable sealing the gap between the seal land outer surface 46 andseal shoe projections 96 within predetermined design tolerances.

Since the spring elements 114 and 116 seal respective gaps between theseal shoes 50 and the seal base 48 as discussed above, the seal assembly38 may be configured without any additional secondary seals. Bycontrast, a seal assembly 800 as shown in FIG. 8 includes at least onesecondary seal 802 for sealing fluid passages 803 adjacent laterallyextending spring beams 804 of a primary seal device 806. The secondaryseal 802 axially engages a respective surface of each seal shoe 808.Friction at this engagement between the secondary seal 802 and the sealshoes 808 may influence movement of the seal shoes 808 radially inwardand outward. More particularly, depending upon a pressure differentialacross the secondary seal 802, the friction may delay and/or slowmovement of the seal shoes 808 and/or completely prevent, for example,movement of the seal shoes 808. Therefore, since the seal assembly 38 ofFIG. 1 may be configured without secondary seals or other seals whichutilize, for example, a rubbing and/or sliding contact, the sealassembly 38 of FIG. 1 may operate without such frictional impediments asdiscussed above with respect to the seal assembly 800 of FIG. 8.

In some embodiments, referring to FIG. 9, one or more or each of thespring elements 114, 116 may have a straight, linear sectional geometrywhen viewed, for example, in a plane coincident with and parallel withthe axial centerline 32; e.g., the plane of FIG. 9. Each respectivespring element 114, 116, for example, may have and follow a straight,linear centerline 150 as that spring element 114, 116 extends from theseal base 48 to the seal shoe 50. In the embodiment of FIG. 9, thecenterline 150 and, thus, the spring element 114, 116 is arrangedparallel with the axial centerline 32. However, in other embodiments,the centerline 150 and, thus, the spring element 114, 116 may bearranged non-parallel with the axial centerline 32.

In some embodiments, one or more or each of the spring elements 114, 116may have and follow a non-straight centerline (e.g., a curvedcenterline, a tortuous centerline, etc.) as that spring element 114, 116extends between the seal base 48 and the seal shoe 50. For example,referring to FIG. 10, one or more or each of the spring elements 114,116 may have a tortuous (e.g., crenulated, wavy, etc.) sectionalgeometry when viewed, for example, in a plane coincident with andparallel with the axial centerline 32; e.g., the plane of FIG. 10. Eachrespective spring element 114, 116, for example, may have and follow acenterline 150′ as that spring element 114, 116 extends from the sealbase 48 to the seal shoe 50. At least a portion (e.g., about 5% to 30%of the element's length) of the centerline 150′ may follow a tortuoustrajectory as that spring element 114, 116 extends from the seal base 48to the seal shoe 50, which portion may (or may not) be located at (e.g.,on, adjacent or proximate) a connection between the spring element 114,116 and the seal base 48.

In some embodiments, referring to FIG. 11, the spring elements 114 and116 associated with a respective seal shoe 50 may be radially aligned.For example, a first radius 154 extends from the axial centerline 32 toan axial point along the centerline 150, 150′ of the HPS spring element114. A second radius 156 extends from the axial centerline 32 to anaxial point along the centerline 150, 150′ of the LPS spring element116. The second radius 156 may be equal to the first radius 154 where,for example, the axial points are similarly situated; e.g., the axialpoints are at the connections to the seal shoe 50, at the connections tothe seal base 48, at midpoints along the spring elements 114, 116, etc.

In some embodiments, referring to FIG. 12, the spring elements 114 and116 associated with a respective seal shoe 50 may be radiallymisaligned. For example, the second radius 156 may be different (e.g.,less, or alternatively greater) than the first radius 154 where, forexample, the axial points are similarly situated; e.g., the axial pointsare at the connections to the seal shoe 50, at the connections to theseal base 48, at midpoints along the spring elements 114, 116, etc.

In some embodiments, referring to FIG. 13, one or more or each of thespring elements 114, 116 may have at least one vent aperture 158; e.g.,a through-hole. This vent aperture 158 extends (e.g., radially) throughthe respective spring element 114, 116. The vent aperture 158 isconfigured to fluidly couple a plenum 160 below (radially inwards of)the spring element 114, 116 with a plenum 162 above (radially outboardof) the spring element 114, 116.

In some embodiments, referring to FIG. 14, each HPS spring element 114extends a first axial distance 164 along the axial centerline 32 fromthe seal base 48 to a respective seal shoe 50. Each LPS spring element116 extends a second axial distance 166 along the axial centerline 32from the seal base 48 to the respective seal shoe 50. The second axialdistance 166 may be different (e.g., greater, or alternatively less)than (or equal to) the first axial distance 164.

In some embodiments, referring to FIG. 1, each HPS spring element 114and each LPS spring element 116 associated with a common seal shoe 50may be connected to different portions of the seal shoe 50. The HPSspring element 114, for example, is connected to the seal shoe mount 98whereas the LPH spring element 116 is connected to the seal shoe base94. Of course, in other embodiments, this may be reversed such that theHPS spring element 114 is connected to the seal shoe base 94 whereas theLPH spring element is connected to the seal shoe mount 98.

In some embodiments, referring to FIGS. 15 and 16, each HPS springelement 114 and each LPS spring element 116 associated with a commonseal shoe 50 may be connected to a common portion of the seal shoe 50.The spring elements 114 and 116 of FIG. 15, for example, are bothconnected to the seal shoe mount 98. In another example, the springelements 114 and 116 of FIG. 16 are both connected to the seal shoe base94.

In some embodiments, referring to FIG. 1, the HPS flange 66 may radiallyoverlap at least a portion of the seal shoes 50. The HPS flange 66 inFIG. 1, for example, radially overlaps at least a portion or an entiretyof each seal shoe mount 98.

In some embodiments, still referring to FIG. 1, the LPS flange 68 mayradially overlap at least a portion of the seal shoes 50. The LPS flange68 in FIG. 1, for example, radially overlaps each seal shoe mount 98 aswell as at least a portion or an entirety of each seal shoe base 94.

In some embodiments, referring to FIG. 17, the seal base 48 may includea seal shoe stop 168. This seal shoe stop 168 is configured to limitradial outward movement of one or more or each of the seal shoes 50. Theseal shoe stop 168, for example, may project axially out from the HPSflange 66 and into the channel 70. This seal shoe stop 168 may beradially engaged (e.g., contacted) by one or more of the seal shoes 50and its mounts 98 when the seal shoe(s) 50 moves a predetermined radialdistance outward from its nominal (at rest) position, thereby limitingradial movement of the seal shoe(s) 50.

In some embodiments, still referring to FIG. 17, the spring system 52may also include a compression spring 170 (e.g., radially) between andengaging (e.g., contacting and/or connected to) the seal base 48 (e.g.,the seal shoe stop 168) and the seal shoe 50 (e.g., the seal shoe mount98). This compression spring 170 may be configured to preload therespective seal shoe 50 in an inward direction.

In some embodiments, still referring to FIG. 17, the spring system 52may also include a compression spring 172 (e.g., radially) between andengaging (e.g., contacting and/or connected to) the seal base 48 (e.g.,the seal shoe stop 168) and one of the spring elements 114, 116 (e.g.,the HPS spring element 114). This compression spring 172 may similarlybe configured to preload the respective seal shoe 50 in an inwarddirection.

In some embodiments, referring to FIG. 18, the seal shoe stop 168 mayhave at least one vent aperture 174; e.g., a through-hole. This ventaperture 174 extends (e.g., radially) through the seal shoe stop 168.The vent aperture 174 is configured to fluidly couple a plenum 176 below(radially inwards of) the seal shoe stop 168 with a plenum (e.g., 80)above (radially outboard of) the seal shoe stop 168.

In some embodiments, still referring to FIG. 18, one or more or eachseal shoe 50 may have at least one vent aperture 178; e.g., athrough-hole. This vent aperture 178 extends (e.g., radially) throughthe respective seal shoe 50. The vent aperture 178 is configured tofluidly couple a plenum 180 below (radially inwards of) the respectiveseal shoe with a plenum (e.g., 80) above (radially outboard of) therespective seal shoe 50.

In some embodiments, referring to FIG. 19, the seal assembly 38 mayinclude one or more dampers 182; e.g., mechanical dampers. Each damper182 may be arranged (e.g., radially) between and engaged with (e.g.,contacting and/or connected to) the seal base 48 and a respective sealshoe 50 (e.g., the seal shoe mount 98). This damper 182 may beconfigured to remove flutter and/or other vibrations during movement ofthe seal shoe 50.

In some embodiments, referring to FIG. 20, one or more or each seal shoe50 may project axially beyond the seal base 48. The seal shoe 50 in FIG.20, for example, projects axially past the HPS flange 66.

In some embodiments, referring to FIG. 21, the spring system 52 mayinclude one or more additional spring elements 184A and 184B (generallyreferred to as “184”) (e.g., spring beams) between and connected to theseal base 48 and a respective seal shoe 50.

Each of the foregoing embodiments may be combined with any one or moreof the other embodiments.

As described above, the rotational equipment assembly 30 of the presentdisclosure may be configured with various different types andconfigurations of rotational equipment. FIG. 22 illustrates one suchtype and configuration of the rotational equipment — a geared turbofangas turbine engine 186. This turbine engine 186 includes variousstationary structures (e.g., bearing supports, hubs, cases, etc.) aswell as various rotors (e.g., rotor disks, shafts, shaft assemblies,etc.) as described below, where the stationary structure 34 and therotating structure 36 can respectively be configured as anyone of theforegoing structures in the turbine engine 186 of FIG. 22, or otherstructures not mentioned herein.

The turbine engine 186 of FIG. 22 extends along the axial centerline 32between an upstream airflow inlet 188 and a downstream airflow exhaust190. The turbine engine 186 includes a fan section 192, a compressorsection 193, a combustor section 194 and a turbine section 195. Thecompressor section 193 includes a low pressure compressor (LPC) section193A and a high pressure compressor (HPC) section 193B. The turbinesection 195 includes a high pressure turbine (HPT) section 195A and alow pressure turbine (LPT) section 195B.

The engine sections 192-195B are arranged sequentially along the axialcenterline 32 within an engine housing 196. This engine housing 196includes an inner case 198 (e.g., a core case) and an outer case 200(e.g., a fan case). The inner case 198 may house one or more of theengine sections 193A-195B; e.g., an engine core. The outer case 200 mayhouse at least the fan section 192.

Each of the engine sections 192, 193A, 193B, 195A and 195B includes arespective rotor 202-206. Each of these rotors 202-206 includes aplurality of rotor blades arranged circumferentially around andconnected to one or more respective rotor disks. The rotor blades, forexample, may be formed integral with or mechanically fastened, welded,brazed, adhered and/or otherwise attached to the respective rotordisk(s).

The fan rotor 202 is connected to a gear train 208, for example, througha fan shaft 210. The gear train 208 and the LPC rotor 203 are connectedto and driven by the LPT rotor 206 through a low speed shaft 211. TheHPC rotor 204 is connected to and driven by the HPT rotor 205 through ahigh speed shaft 212. The shafts 210-212 are rotatably supported by aplurality of bearings 214. Each of these bearings 214 is connected tothe engine housing 196 by at least one stationary structure such as, forexample, an annular support strut.

During operation, air enters the turbine engine 186 through the airflowinlet 188. This air is directed through the fan section 192 and into acore gas path 216 and a bypass gas path 218. The core gas path 216extends sequentially through the engine sections 193A-195B. The airwithin the core gas path 216 may be referred to as “core air”. Thebypass gas path 218 extends through a bypass duct, which bypasses theengine core. The air within the bypass gas path 218 may be referred toas “bypass air”.

The core air is compressed by the compressor rotors 203 and 204 anddirected into a combustion chamber 220 of a combustor in the combustorsection 194. Fuel is injected into the combustion chamber 220 and mixedwith the compressed core air to provide a fuel-air mixture. This fuelair mixture is ignited and combustion products thereof flow through andsequentially cause the turbine rotors 205 and 206 to rotate. Therotation of the turbine rotors 205 and 206 respectively drive rotationof the compressor rotors 204 and 203 and, thus, compression of the airreceived from a core airflow inlet. The rotation of the turbine rotor206 also drives rotation of the fan rotor 202, which propels bypass airthrough and out of the bypass gas path 218. The propulsion of the bypassair may account for a majority of thrust generated by the turbine engine186, e.g., more than seventy-five percent (75%) of engine thrust. Theturbine engine 186 of the present disclosure, however, is not limited tothe foregoing exemplary thrust ratio.

The rotational equipment assembly 30 may be included in various turbineengines other than the one described above as well as in other types ofrotational equipment. The rotational equipment assembly 30, for example,may be included in a geared turbine engine where a gear train connectsone or more shafts to one or more rotors in a fan section, a compressorsection and/or any other engine section. Alternatively, the rotationalequipment assembly 30 may be included in a turbine engine configuredwithout a gear train. The rotational equipment assembly 30 may beincluded in a geared or non-geared turbine engine configured with asingle spool, with two spools (e.g., see FIG. 22), or with more than twospools. The turbine engine may be configured as a turbofan engine, aturbojet engine, a propfan engine, a pusher fan engine or any other typeof turbine engine. The present disclosure therefore is not limited toany particular types or configurations of turbine engines or rotationalequipment.

While various embodiments of the present disclosure have been described,it will be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible within the scope of thedisclosure. For example, the present disclosure as described hereinincludes several aspects and embodiments that include particularfeatures. Although these features may be described individually, it iswithin the scope of the present disclosure that some or all of thesefeatures may be combined with any one of the aspects and remain withinthe scope of the disclosure. Accordingly, the present disclosure is notto be restricted except in light of the attached claims and theirequivalents.

What is claimed is:
 1. An assembly for rotational equipment, comprising:a plurality of seal shoes arranged about a centerline in an annulararray, the plurality of seal shoes comprising a first seal shoe; a sealbase circumscribing the plurality of seal shoes; and a spring systemconnecting the plurality of seal shoes to the seal base, the springsystem including a first spring element and a second spring element; thefirst spring element extending in a first direction from the seal baseto the first seal shoe; and the second spring element extending in asecond direction from the seal base to the first seal shoe, the seconddirection opposite the first direction.
 2. The assembly of claim 1,wherein the seal base includes a first flange that overlaps the firstseal shoe in a third direction that is perpendicular to the firstdirection; and the first spring element extends in the first directionfrom the first flange to the first seal shoe.
 3. The assembly of claim2, wherein the seal base further includes a second flange that overlapsthe first seal shoe in the third direction; and the second springelement extends in the second direction from the second flange to thefirst seal shoe.
 4. The assembly of claim 1, wherein a first radiusextends from the centerline to the first spring element; a second radiusextends from the centerline to the second spring element; and the firstradius is equal to the second radius.
 5. The assembly of claim 1,wherein a first radius extends from the centerline to the first springelement; a second radius extends from the centerline to the secondspring element; and the first radius is different than the secondradius.
 6. The assembly of claim 1, further comprising a compressionspring between and engaged with the seal base and the first springelement.
 7. The assembly of claim 1, further comprising a compressionspring between and engaged with the seal base and the first seal shoe.8. The assembly of claim 1, further comprising a damper between andconnected to the seal base and the first seal shoe.
 9. The assembly ofclaim 1, wherein the seal base includes a seal shoe stop configured tolimit outward movement of the first seal shoe.
 10. The assembly of claim9, wherein a vent aperture extends through the seal shoe stop.
 11. Theassembly of claim 1, wherein a vent aperture extends through the firstspring element or the first seal shoe.
 12. The assembly of claim 1,wherein the first seal shoe projects axially beyond the seal base. 13.The assembly of claim 1, wherein the first spring element extends in thefirst direction from the seal base to the first seal shoe for a firstdistance; the second spring element extends in the second direction fromthe seal base to the first seal shoe for a second distance; and thesecond distance is different than the first distance.
 14. The assemblyof claim 1, wherein at least one of the first spring element has astraight, linear sectional geometry as the first spring element extendsfrom the seal base to the first seal shoe; or the second spring elementhas a straight, linear sectional geometry as the second spring elementextends from the seal base to the first seal shoe.
 15. The assembly ofclaim 1, wherein at least one of at least a portion of the first springelement has a tortuous sectional geometry as the first spring elementextends away from the seal base towards the first seal shoe; or at leasta portion of the second spring element has a tortuous sectional geometryas the second spring element extends away from the seal base towards thefirst seal shoe.
 16. The assembly of claim 1, wherein the spring systemfurther includes one or more additional spring elements connected to andextending between the seal base and the first seal shoe.
 17. Theassembly of claim 1, wherein the first seal shoe has a first seal shoelateral width, and at least one of the first spring element has a firstspring element lateral width that is equal to the first seal shoelateral width; or the second spring element has a second spring elementlateral width that is equal to the first seal shoe lateral width. 18.The assembly of claim 1, further comprising: a stationary structure; arotating structure configured to rotate about the centerline; and a sealassembly including the plurality of seal shoes, the seal base and thespring system, the seal assembly configured to seal a gap between thestationary structure and the rotating structure; wherein the pluralityof seal shoes are arranged circumferentially about and sealingly engagethe rotating structure; and wherein the seal base is mounted to thestationary structure.
 19. An assembly for rotational equipment,comprising: a plurality of seal shoes arranged about a centerline in anannular array, the plurality of seal shoes comprising a first seal shoe;a seal base extending circumferentially around the plurality of sealshoes and the centerline; and a spring system connecting the pluralityof seal shoes to the seal base, the spring system including a firstspring element and a second spring element; the first spring elementbetween and connected to the seal base and the first seal shoe; thesecond spring element between and connected to the seal base and thefirst seal shoe; and the first seal shoe between the first springelement and the second spring element.
 20. An assembly for rotationalequipment, comprising: a plurality of seal shoes arranged about acenterline in an annular array, the plurality of seal shoes comprising afirst seal shoe and a second seal shoe; a seal base extendingcircumferentially around the plurality of seal shoes and the centerline;and a spring system connecting the plurality of seal shoes to the sealbase, the spring system including a first spring element, a secondspring element, a third spring element and a fourth spring element; thefirst spring element arranged towards a first side of the first sealshoe, and the first spring element connected to and between the firstseal shoe and the seal base; the second spring element arranged towardsa second side of the first seal shoe opposite the first side of thefirst seal shoe, and the second spring element connected to and betweenthe first seal shoe and the seal base; the third spring element arrangedtowards a first side of the second seal shoe, and the third springelement connected to and between the second seal shoe and the seal base;the fourth spring element arranged towards a second side of the secondseal shoe opposite the first side of the second seal shoe, and thefourth spring element connected to and between the second seal shoe andthe seal base; the first seal shoe and the second seal shoe laterallyseparated by a first lateral distance; and the first spring element andthe third spring element laterally separated by a second lateraldistance that is equal to the first lateral distance.